#!/usr/bin/python3
import sys

def search_distinct_set(datastream, length):
    index = length
    while len(set(datastream[index - length:index])) != length:
        index += 1
        #print(window, list(set(window)))
    return index

def solution(length):
    for line in sys.stdin:
        print(f'first marker after character {search_distinct_set(line, length)}')

if sys.argv[1] in '1':
    solution(4)
else:
    solution(14)